A global health problem caused by arsenic from natural sources

Arsenic is a carcinogen to both humans and animals. Arsenicals have been associated with cancers of the skin, lung, and bladder. Clinical manifestations of chronic arsenic poisoning include non-cancer end point of hyper- and hypo-pigmentation, keratosis, hypertension, cardiovascular diseases and diabetes. Epidemiological evidence indicates that arsenic concentration exceeding 50 mug l(-1) in the drinking water is not public health protective. The current WHO recommended guideline value for arsenic in drinking water is 10 mug l(-1), whereas many developing countries are still having a value of 50 mug 1(-1). It has been estimated that tens of millions of people are. at risk exposing to excessive levels of arsenic from both contaminated water and arsenic-bearing coal from natural sources. The global health implication and possible intervention strategies were also discussed in this review article. (C) 2003 Elsevier Ltd. All rights reserved.

The application of adaptive partitioned random search in feature selection problem

Feature selection is one of important and frequently used techniques in data preprocessing. It can improve the efficiency and the effectiveness of data mining by reducing the dimensions of feature space and removing the irrelevant and redundant information. Feature selection can be viewed as a global optimization problem of finding a minimum set of M relevant features that describes the dataset as well as the original N attributes. In this paper, we apply the adaptive partitioned random search strategy into our feature selection algorithm. Under this search strategy, the partition structure and evaluation function is proposed for feature selection problem. This algorithm ensures the global optimal solution in theory and avoids complete randomness in search direction. The good property of our algorithm is shown through the theoretical analysis.

Localizing the relativistic electron

A causally well-behaved solution of the localization problem for the free electron is given, with natural space-time transformation properties, in terms of Dirac's position operator x. It is shown that, although x is not an observable in the usual sense, and has no positive-energy (generalized) eigenstates, the four-vector density (rho(x, t), j(x, t)/c) is observable, and can be localized arbitrarily precisely about any point in space, at any instant of time, using only positive energy states. A suitable spin operator can be diagonalized at the same time.

Neurology of ciguatera

Ciguatera is a widespread ichthyosarcotoxaemia with dramatic and clinically important neurological features. This severe form of fish poisoning may present with either acute or chronic intoxication syndromes and constitutes a global health problem. Ciguatera poisoning is little known in temperate countries as a potentially global problem associated with human ingestion of large carnivorous fish that harbour the bioaccumulated ciguatoxins of the photosynthetic dinoflagellate Gambierdiscus toxicus. This neurotoxin is stored in the viscera of fish that have eaten the dinoflagellate and concentrated it upwards throughout the food chain towards progressively larger species, including humans. Ciguatoxin accumulates in all fish tissues, especially the liver and viscera, of at risk species. Both Pacific (P-CTX-1) and Caribbean (C-CTX-1) ciguatoxins are heat stable polyether toxins and pose a health risk at concentrations above 0.1 ppb. The presenting signs of ciguatera are primarily neurotoxic in more than 80% of cases. Such include the pathognomonic features of postingestion paraesthesiae, dysaesthesiae, and heightened nociperception. Other sensory abnormalities include the subjective features of metallic taste, pruritis, arthralgia, myalgia, and dental pain. Cerebellar dysfunction, sometimes diphasic, and weakness due to both neuropathy and polymyositis may be encountered. Autonomic dysfunction leads to hypotension, bradycardia, and hypersalivation in severe cases. Ciguatoxins are potent, lipophilic sodium channel activator toxins which bind to the voltage sensitive (site 5) sodium channel on the cell membranes of all excitable tissues. Treatment depends on early diagnosis and the early administration of intravenous mannitol. The early identification of the neurological features in sentinel patients has the potential to reduce the number of secondary cases in cluster outbreaks.

Optimum coal properties and engineering processes for CO2 geosequestration in Coal

CO2 Geosequestration is seen by many worldwide scientists and engineers as a leading prospective solution to the global warming problem arising from excessive CO2 and other greenhouse gas emissions. CO2 geosequestration in coal seams has two important strategic benefits: the process has an extremely low risk of leakage, due to the adsorbed state of the CO2 and the known reservoir context of essentially-zero leakage into which it is be injected; the second benefit arises from the valuable by-product, clean burning coalbed methane gas. This paper presents the authors’ experience, knowledge and perspective on what coal properties and engineering processes would favour implementing a demonstration or commercial CO2 storage-in-coal project, in Queensland, Australia. As such, it may be considered a template for screening studies to select the optimum coal seam reservoir, and for preliminary studies in designing the injection system and predicting production response to the technology. The paper concludes by examining the current knowledge gaps of CO2 geosequestration in coal, identifying further basic and applied research topics.

Ciguatera: Australian perspectives on a global problem

Ciguatera is a global disease caused by the consumption of certain warm-water fish that have accumulated orally effective levels of sodium channel activator toxins (ciguatoxins) through the marine food chain. Symptoms of ciguatera arising from the consumption of ciguateric fish include a range of gastrointestinal, neurological and cardiovascular disturbances. This review examines progress in our understanding of ciguatera from an Australian perspective, especially the laboratory-based research into the problem that was initiated by the late "Bob" Endean at the University of Queensland.

Reflections on the statistical analysis of personality and norms in war, peace, and prejudice: Are deviant minorities the problem?

The compelling quality of the Global Change simulation study (Altemeyer, 2003), in which high RWA (right-wing authoritarianism)/high SDO (social dominance orientation) individuals produced poor outcomes for the planet, rests on the inference that the link between high RWA/SDO scores and disaster in the simulation can be generalized to real environmental and social situations. However, we argue that studies of the Person × Situation interaction are biased to overestimate the role of the individual variability. When variables are operationalized, strongly normative items are excluded because they are skewed and kurtotic. This occurs both in the measurement of predictor constructs, such as RWA, and in the outcome constructs, such as prejudice and war. Analyses of normal linear statistics highlight personality variables such as RWA, which produce variance, and overlook the role of norms, which produce invariance. Where both normative and personality forces are operating, as in intergroup contexts, the linear analysis generates statistics for the sample that disproportionately reflect the behavior of the deviant, antinormative minority and direct attention away from the baseline, normative position. The implications of these findings for the link between high RWA and disaster are discussed.

Localizing a global discipline - Designing new planning programs in Sri Lanka

In order to be relevant and useful in a fragmented developing country context, community and regional planning needs to shift away from the use of rigid tools to more flexible, adaptive approaches. An international review of planning curricula indicated a widespread consensus with respect to key competencies required of planners. This understanding was used in the development of new teaching programs at three Sri Lankan universities. Complementing the technical core knowledge areas, strong emphases on problem structuring, critical and strategic thinking, and the understanding of the political and institutional contexts appear to be crucial to making the agenda of planning for sustainable development more than a fashionable cliche. In order for these core areas to have relevance in a developing country context, however, planning curricula need to achieve a balance between local priorities and a global perspective.

Global behavior of positive solutions of nonlinear three-point boundary value problems

We investigate the structure of the positive solution set for nonlinear three-point boundary value problems of the form u('') + h(t) f(u) = 0, u(0) = 0, u(1) = lambdau(eta), where eta epsilon (0, 1) is given lambda epsilon (0, 1/n) is a parameter, f epsilon C ([0, infinity), [0, infinity)) satisfies f (s) > 0 for s > 0, and h epsilon C([0, 1], [0, infinity)) is not identically zero on any subinterval of [0, 1]. Our main results demonstrate the existence of continua of positive solutions of the above problem. (C) 2004 Elsevier Ltd. All rights reserved.

Prioritizing global conservation efforts

One of the most pressing issues facing the global conservation community is how to distribute limited resources between regions identified as priorities for biodiversity conservation(1-3). Approaches such as biodiversity hotspots(4), endemic bird areas(5) and ecoregions(6) are used by international organizations to prioritize conservation efforts globally(7). Although identifying priority regions is an important first step in solving this problem, it does not indicate how limited resources should be allocated between regions. Here we formulate how to allocate optimally conservation resources between regions identified as priorities for conservation - the 'conservation resource allocation problem'. Stochastic dynamic programming is used to find the optimal schedule of resource allocation for small problems but is intractable for large problems owing to the curse of dimensionality(8). We identify two easy- to- use and easy- to- interpret heuristics that closely approximate the optimal solution. We also show the importance of both correctly formulating the problem and using information on how investment returns change through time. Our conservation resource allocation approach can be applied at any spatial scale. We demonstrate the approach with an example of optimal resource allocation among five priority regions in Wallacea and Sundaland, the transition zone between Asia and Australasia.

Probabilistic visual recognition of artificial landmarks for simultaneous localization and mapping

Probabilistic robotics most often applied to the problem of simultaneous localisation and mapping (SLAM), requires measures of uncertainty to accompany observations of the environment. This paper describes how uncertainty can be characterised for a vision system that locates coloured landmarks in a typical laboratory environment. The paper describes a model of the uncertainty in segmentation, the internal cameral model and the mounting of the camera on the robot. It explains the implementation of the system on a laboratory robot, and provides experimental results that show the coherence of the uncertainty model.

Evidence for a global Wolbachia replacement in Drosophila melanogaster

Wolbachia are maternally inherited intracellular α-Proteobacteria found in numerous arthropod and filarial nematode species [1, 2 and 3]. They influence the biology of their hosts in many ways. In some cases, they act as obligate mutualists and are required for the normal development and reproduction of the host [4 and 5]. They are best known, however, for the various reproductive parasitism traits that they can generate in infected hosts. These include cytoplasmic incompatibility (CI) between individuals of different infection status, the parthenogenetic production of females, the selective killing of male embryos, and the feminization of genetic males [1 and 2]. Wolbachia infections of Drosophila melanogaster are extremely common in both wild populations and long-term laboratory stocks [6, 7 and 8]. Utilizing the newly completed genome sequence of Wolbachia pipientis wMel [9], we have identified a number of polymorphic markers that can be used to discriminate among five different Wolbachia variants within what was previously thought to be the single clonal infection of D. melanogaster. Analysis of long-term lab stocks together with wild-caught flies indicates that one of these variants has replaced the others globally within the last century. This is the first report of a global replacement of a Wolbachia strain in an insect host species. The sweep is at odds with current theory that cannot explain how Wolbachia can invade this host species given the observed cytoplasmic incompatibility characteristics of Wolbachia infections in D. melanogaster in the field [6].

Least energy solutions of a critical Neumann problem with a weight

We investigate the effect of the coefficient of the critical nonlinearity for the Neumann problem on the existence of least energy solutions. As a by-product we establish a Sobolev inequality with interior norm.